1. Field of the Invention
This invention relates to a solid cast composition containing surfactants, a chlorine source, optional alkalinity sources and optional detergent builders.
2. Background
Detergent products formulated with high levels of an active chlorine source, such as for example a mono- or dichloro(iso)cyanurate, tend to be unstable in response to a variety of conditions. Heat, acidity, and moisture are conditions especially which tend to promote instability of active chlorine sources. For example, heat normally causes the active chlorine source to liberate chlorine. Thus, manufacturing conditions and storage conditions dictate that constraints be placed on the usage of active chlorine sources such as the mono- or dichloro(iso)cyanurates.
Active chlorine sources are typically affected by low pH conditions which favor chlorine liberation. Thus, the presence of acidic materials in proximity to the active chlorine source must be considered in the manufacture of active chlorine source containing products and in the storage of such products.
Another factor which must be taken into consideration in the manufacture of a detergent product containing an (iso)cyanurate is water. Water generally promotes the liberation of chlorine from an (iso)cyanurate. In a detergent product containing a free fatty acid, a strong base such as sodium or potassium hydroxide and an active chlorine source, the reaction between the strong base and the fatty acid to form soap will also liberate water. The reaction of the strong base and the fatty acid to form a soap is an exothermic reaction.
As previously noted, the liberation of heat in an exothermic reaction promotes chlorine liberation from an active chlorine source. The water which is generated from the reaction of the strong base and the free fatty acid promotes the dispersion of the strong base and the fatty acid. These effects, especially when combined, might be thought of as almost similar to a catalytic effect in promoting or accelerating the reaction. As the reaction between the strong base and the free fatty acid proceeds further, quantities of heat are generated and more chlorine is liberated from the active chlorine source. In other words, these effects render manufacturing of such active chlorine containing detergent products very difficult.
If the source of alkalinity (the strong base) is sufficiently depleted, the chlorine generated may combine with the water to form an acid and to further reduce the pH in the vicinity of the active chlorine source. This, in turn, also further promotes the liberation of chlorine from the active chlorine source. Together with the previously mentioned problems, this effect further adds to the challenge of producing such a product.
Thus, one skilled in the art will normally avoid the use of ingredients which liberate chlorine gas which is a potentially flammable mixture and which could spontaneously ignite. An alternative to avoiding the use of certain ingredients which favor chlorine generation from an active chlorine source is to stabilize the conflicting ingredients. Such attempts to stabilize conflicting ingredients are discussed below.
U.S. Pat. No. 3,908,045 issued to Alterman et al., Sep. 23, 1975 discloses particles of a fluidizable substance coated with a non-aqueous solution. Disclosures similar to U.S. Pat. No. 3,908,045 are found in U.S. Pat. No. 3,983,254 issued to Alterman et al., Sep. 28, 1976.
Chun et al., in U.S. Pat. No. 4,655,780 issued Apr. 7, 1987 discloses hard spherical bleaching particles utilizing an active halogen oxidizing material. U.S. Pat. No. 4,657,784 to Olson et al., issued Apr. 14, 1987 discusses the use of encapsulated halogen bleaches. U.S. Pat. No. 4,731,195 issued Mar. 15, 1988 to Olson et al., (a divisional of U.S. Pat. No. 4,657,784), contains similar disclosures.
The use of an active halogen bleach which is encapsulated with a synthetic detergent such as sodium octyl sulfonate is disclosed in U.S. Pat. No. 4,681,914 issued Jul. 21, 1987 to Olson et al. as well as in U.S. Pat. No. 5,407,598 issued Apr. 18, 1995 to Olson et al.
U.S. Pat. No. 5,213,705 which issued May 25, 1993 to Olson also discloses an active halogen bleach which is encapsulated with a synthetic detergent. Chun et al., in U.S. Pat. No. 4,707,160, issued Nov. 17, 1987, discloses particles with a core containing a halogen bleach. U.S. Pat. No. 5,133,892 issued Jul. 28, 1992 to Chun et al., discloses a multi layer detergent tablet.
Aronson et al., in U.S. Pat. No. 4,863,632 issued Sep. 5, 1989 discloses a bleaching particle having an oxidizing material surrounded by a polycarbonate coating. U.S. Pat. No. 5,358,653 issued to Gladfelter et al., Oct. 25, 1994 discloses a cleaning product containing a chlorine source.
None of the foregoing references discloses the combination of ingredients in a solid cast composition which are utilized in the present invention to prepare a stable active chlorine containing detergent composition. The method of manufacture of the composition of the present invention results in a surprisingly stable solid cast composition with ingredients that were previously considered incompatible with an active chlorine source.
The free fatty acid component of the invention is typically avoided in a cleaning product because the presence of hard water ions results in the formation of insoluble soap scum. The active chlorine source, while desirable for bleaching and disinfecting, is often avoided because of the problem of stabilizing the active chlorine source against the liberation of chlorine gas. The alkali metal hydroxide is often avoided because of the high pH potential when the alkali metal hydroxide is contacted with water. The detergent builders, while innocuous in most detergent products, are typically friable high melting point solids having hygroscopic properties. Thus, the inclusion of the detergent builder may aggravate the liberation of chlorine gas, raise the temperature required to disperse the remaining components of the solid cast detergent composition, and cause the solid cast detergent composition to be utilized unevenly.
Surprisingly, by practicing the present invention as described below, the challenge of manufacturing such a highly desirable product becomes quite manageable. Specifically, the present invention provides four important advantages: (1) chlorine liberation is minimized or eliminated; (2) the fatty acid reacts upon the addition of water with the alkali metal hydroxide to form a soap rather than to form a soap scum; (3) the water preferentially reacts with the fatty acid and the alkali metal hydroxide rather than liberating chlorine until the alkali metal source is largely depleted into the wash liquor; and (4) the detergent builder is not free to act hygroscopically. Moreover, the detergent builder does promote dispersion of the remaining ingredients in the solid cast detergent composition.
To the extent that the foregoing references are applicable to the present invention they are herein specifically incorporated by reference. Temperatures given herein are degrees Celsius unless otherwise indicated. Throughout the specification and claims, percentages and ratios are by weight unless otherwise indicated. Percentages are based upon the combined weight of the components recited in the pertinent claims. Ranges and ratios given herein may be combined.